package Network;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

public class HomeworkUdpEchoServer {
    private DatagramSocket socket = null;

    public HomeworkUdpEchoServer(int port) throws SocketException {
        socket = new DatagramSocket(port);
    }

    public void start() throws IOException {
        // 启动服务器
        System.out.println("服务器启动.");
        while(true){
            // 1.读取请求并解析
            DatagramPacket requestPacket = new DatagramPacket(new byte[4096],4096);
            socket.receive(requestPacket);
            String request = new String(requestPacket.getData(),0,requestPacket.getLength());


            // 2.根据请求计算响应
            String response = process(request);

            //3.把响应返回给客户端
            DatagramPacket responsePacket = new DatagramPacket(response.getBytes(),response.getBytes().length,
                    requestPacket.getSocketAddress());
            socket.send(responsePacket);

            System.out.printf("[%s : %d] req : %s, resp : %s\n",requestPacket.getAddress().toString(),requestPacket.getPort(),
                    request,response);

        }
    }

    private String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        HomeworkUdpEchoServer server = new HomeworkUdpEchoServer(9090);
        server.start();
    }
}
